Apparatus for the recovery of volatilizable metals



1944- M. PIDGEON APPARATUS FOR THE RECOVERY OF VOLATILIZABLE METALS Filed Jan. 8, 1942 Fig. 4

Fig.5

lNVE/VTOR:

LLOYD MONTGOMERY P/Db'EO/V 42.; 4 4

ATTORNEY.

Patented Nov. 14, 1944 APPARATUS FOR THE RECOVERY OF VOLATILIZABLE METALS Lloyd Montgomery Pidgeon, Rockcliife Park,

Ontario, Canada, asslgnor, by mesne assignments, to Dominion Magnesium Limited. Toronto, Ontario, Canada, a corporation of Canada Application January 8, 1942, Serial No. 426,008

Canada December 18, 1941 14 Claims.

This invention relates to an apparatus for the recovery of volatilizable metals and particularly to a retort and condenser for the thermal treatment of metal-containing materials and the recovery of volatilizable metals, such as magnesium and calcium, in substantially pure form.

In my copending application, Serial No. 417,810, filed November 3, 1941, there is described a method and apparatus for recovering volatilizable metals and the present invention is directed to another form of apparatus for carrying out the method described.

Each of the forms of apparatus described in the copending application referred to includes a retort having a reduction zone located within a furnace and a condensing zone extending exteriorly of the furnace. a removable condenser in the latter zone, a removable closure for the retort and condenser, and a conduit leading through the closure for producing a vacuum in the retort. A disadvantage of this arrangement is that, in order to remove the closure for charging the retort or for removal of condensed metals therefrom, the vacuum conduit must be disconnected from or carried with the closure. Such a step constitutes a drawback in the practical operation of the device.

It is an object of the present invention to provide an apparatus of simple structure and convenient manufacture wherein the various operat-- ing steps necessary for carrying out the process of recovering volatilizable metals may be readily and quickly accomplished in a satisfactory manner. To this end the invention contemplates the provision of a retort of the type referred to having a closure plate and. a vacuum passage located in a wall of the retort separate from the closure plate. The invention further contemplates the provision of means associated with said passage for connecting it to a vacuum conduit, of means associated with the closure plate for aiding in an eflicient manner the production of vacuum in closure member of the apparatus illustrated in Figure 3, and

Figure 5 is a top plan view of the apparatus illustrated in Figure 3 with the closure member removed.

Referring to Figure 1 of the drawing, I is a metal retort adapted to be associated with a furnace 2. The retort includes a reduction zone 3 extending into the furnace in which it is externally heated in any desired way and a condenser zone 4 extending exteriorly of the furnace. Within the condenser zone is located a removable condenser 5 the inner end of which is tapered, as at 6, to seat snugly against a complementary bevelled shoulder I in the wall of the retort. The internal diameter of the condenser should be at least as great as, and preferably somewhat greater than that of the reduction zone of the retort. The retort and condenser constitute a unit, any desired number of which may be used in one furnace. The external diameter of the condenser is sufficiently less than the internal diameter of the retort in the condensing zone so that due clearance is provided for easy removal of the condenser. The condenser seating arrangement prevents escape of vapours between the condenser and retort wall.

The outer end of the retort extends a short distance beyond the outer end of the condenser and is provided with a flange 8.

The unit is provided with a removable closure device which includes a plate 9 adapted to rest upon the end of the condenser and a closure plate Ill adapted to rest on the retort flange 8 and to be secured thereto by any suitable clamping means II. The plate 9 has a central opening 9 therein.

Means are provided for maintaining a positive pressure on the plate 9 whereby the condenser is pressed snugly against the tapered seat I at all times when the closure device is in place. Such means, in the present instance, comprises a plurality of coil springs l2 arranged between the plates 9 and 10 by means of bolts or the like I3.

Means for producing a vacuum within the retort comprises a conduit I4 having its intake in the side wall of the retort between the two plates 9 and Ill. Generally speaking, just sufficient space is provided between the closure plates 9 and ID to permit of the arrangement of the vacuum intake within such space.

A gasket I5 is preferably inserted between the flange 8 and plate Ill.

Cooling means are provided at the condenser end of the retort and, as shown, comprises an annular chamber I6 through which cooling water may circulate in contact with the wall of the retort. If desired, an internal cooler may also be provided adjacent the end of the condenser.

An auxiliary means for condensing vapours of, for instance, sodium and like metals of relatively high vapour pressure and for removing such metals independently of, say, magnesium is provided and comprises, as shown, a metal disc I! suspended in spaced relation from the plate 9 by means of supporting members l8. The disc I! is in diameter substantially equal to the internal diameter of the condenser and is provided with a central opening l9.

At the outlet end of the reducing zone of the retort is located a baflle or thermal radiation shield, 20 having perforations 2| therein for the passage of metallic vapours formed in the reducing zone.

Referring to Figure 2, the retort l is similar in structure to that shown in Figure 1 and contains the removable condenser 5. A removable closure device, also similar to that shown in Figure 1, is

provided. However, in order to provide a more.

Referring to Figures 3, 4 and the retort l and removable condenser 5, also similar in general structure to those shown in Figure 1, are provided. In this form, an annular vacuum chamber 25, which may be triangular in cross-section, constitutes a manifold located in adjoining relation to the under side of flange Band having a plurality of narrow slot-like inlets 26 extending through the flange.

A closure device for the retort comprises a plate 21 having a portion 21% dished to permit free communication of the inlets 26 with the interior of the retort. v In order that withdrawal of gases from the retort to produce vacuum therein may be directed from the central area thereof for more eflicient operation, a disc 29 provided with a central opening 30 is suspended from the plate 21 by means of webs 3| and has marginal sealing engagement with the edge of the retort.

A closure plate 32 for the condenser 5 may be integral with the disc 29, as shown.

-An annular cooler 33 which may be triangular in cross-section is provided. It will be observed that the triangular crosssectional shape of the cooler and vacuum manifold conserves space and permits of an interfltting overlapping arrangement of the same for efficiency of the cooling arrangement.

Internal coolers may be provided in the forms shown in Figures 2 and 3 if desired.

In the operation of all forms of the apparatus, the closure device, condenser and baflie plate are readily removed in order that a charge of material may be fed into the reducing or heating zone of the retort and replaced preparatory to heating of the retort in' the furnace to volatilize the metal of the charge.

The charge is heated to the desired degree of temperature and the retort is subjected to a suitable degree of vacuum as required. -As metal vapours are evolved from the charge they pass through the baille into the condenser. vapours of metal of low vapour pressure condense on the walls of the condenser in the initial zone, while those of metal of higher vapour pressure pass through the opening I9 in the disc H to the secondary condensing zone, where they condense and collect independently.

Upon completion of the volatilization process and after necessary cooling, the closure device is removed and the condenser withdrawn for removal of the condensed metals and placing of a fresh charge.

It will be Observed that, in all forms of the apparatus, the closure device and condenser may beremoved and replaced with little effort and a minimum of disturbance of other parts of the apparatus. Moreover, in all forms but particularly that illustrated in Figures 3, 4 and 5, a most eilicient means for producing vacuum in the retort is provided. It will be apparent that various changes may be made in the apparatus embodying the present invention without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In apparatus for volatilizing metals, a retort having a volatilizing zone and a condensing zone therein, a removable condenser in the latter zone, a removable closure device for the .condenser and retort comprising a pair of spaced apart plates, one bearing upon the end of the condenser and the other bearing upon the end of the retort, and means forming a vacuum passage leading through the wall of the retort at a point between said plates.

2. In apparatus for volatilizing metals, a retort having a volatilizing zone and a condensing zone therein, a removable condenser in the latter zone, a removable closure device for the condenser and retort comprising a pair of spaced apart plates, one bearing upon the end of the condenser and the other bearing upon the end of the retort, and a vacuum conduit having an inlet in the wall of the retort at a point between said plates.

3. In apparatus for volatilizing metals, a retort having a volatilizing zone and a condensing zone therein, a removable condenser in the latter zone, a removable closure device for the condenser and retort comprising a pair of spaced apart plates, an annular vacuum manifold extending around the retort adjacent the said closure device, said-manifold having a plurality of inlets extending through the wall of the retort at points located between said plates.

4. In apparatus for volatilizing metals, a retort having a volatilizing zone adjacent one end and a condensing zone adjacent the other end, a removable condenser in the latter zone, a removable closure device for the condenser and retort comprising a pair of spaced apart plates, said retort having a flange at said other end and one of said plates bearing upon the flange, the other plate bearing upon the end of the condenser, an annular vacuum manifold extending around the retort in contact with said flange, said manifold having a plurality of slot-like inlets extending through the wall of the retort at points adjoining said flange.

5. In apparatus for volatilizing metals as de-- fined in claim 4, an annular cooler extending around said retort in adjoining relation to said manifold.

6. In apparatus for volatilizing metals, 9. retort having a volatilizing zone adjacent one end and a condensing zone adjacent the other end, a removable condenser in the latter zone, a removable closure device for the condenser and retort comprising a pair of spaced apart plates, said retort having a flange at said other end, one of said plates being dished and having its marginal portion bearing upon a portion of the flange, the

7. Apparatus for volatizing metals as defined in claim 6, wherein said manifold is substantially triangular in cross-section and has an outer wall extending in right angular relation to said flange, and including a vacuum conduit having an inlet in said wall. a

' 8. Apparatus for volatilizing metals as defined in claim 8, wherein said manifold is substantially triangular in cross-section and has an outer wall extending in right angular relation to said dams. and including a vacuum conduit having an inlet in said wall, and an annular cooler also substantially triangular in cross-section extending around the retort, said cooler having one wall in contact with said manifold and another wall in contact with said retort.

9. Apparatus for volatilising metals as defined in claim 6, including a plate suspended from the dished portion of said dished plate and having marginal bearing contact with the end of the retort, said suspended plate having a central opening therein.

- 10. In apparatus for volatilizing metals, a retort having a volatilizing zone adiacent one end and a condensing zone adjacent the other end, a removable condenser in the latter zone, a removable closure device for the retort and condenser comprising a dished plate, said retort having a flangeatsaidotherendandsaidplatehavingits marginal portion bearing upon a portion of the dance, a second plate spaced from the dished plate, webs connecting the second plate to the dished. plate, said second plate having a flange bearing upon the end of the retort, a shoulder bearingupontheendofthecondenseranda central opming. and an annular vacuum manifoldcxtendingaronmdtheretortincontact with theflange, said manifold having a plurality of slot-like inlets extending through said flange and opening into the dished portion of the dished plate.

11. Apparatus for producing metallic magnesium by thermal reduction and sublimation comprising a furnace, a metal retort having a reducing and volatilizing portion within the furnace and a condensing portion without the furnace, a removable condenser within the condensing portion, means for producing vacuum within the retort, a gas-tight closure for the retort and a perforated closure for the removable condenser, said closures and the removable condenser being removable without moving the vacuum producing means.

12. Apparatus for producing metallic magnesium by thermal reduction and sublimation comprising a furnace, a metal retort having a reducing and volatilizing portion within the furnace and a condensing portion without the furnace, a removable condenser within the condensing portion, a gas tight closure for the retort, a closure having an opening therein for the outer end of the removable condenser, said closures deflning a vacuum space, a vacuum line and means to connect the vacuum line into said space.

13. In apparatus for producing metallic 'magnesium by thermal reduction and sublimation, a retort having a reducing chamber, a condensing chamber and a vacuum chamber, a cover for the retort, said cover constituting one wall of the vacuum chamber, a closure plate for the condensing chamber, said closure plate constituting another wall of the vacuum chamber and having an opening for communicating vacuum from the vacuum chamber to the condensing chamber; and a vacuum line leading from the vacuum chamber to a source of vacuum.

14. In a retort for the production of metallic magnesium by reduction of magn s um bearing material with a reducing agent, a reducing chamber permanently located in a furnace maintained at the reduction temperature for the magnesium bearing material, a condenser chamber extending outside the furnace and a vacuum chamber in the outer end of the retort, each such chamber communicating directly with the adjacent line.

LLOYD MONTGOMERY PIDGEON. 

